Electronic musical instrument



Aug. 23, 1960 T. J. GEORGE ELECTRONIC MUSICAL INSTRUMENT Filed March 26, 1956 United States Patent @hice 2,949,804 ELECTRONIC MUSICAL INSTRUMENT Thomas J. George, 11671 Victory Blvd., North Hollywood, Calif.

Filed Mar. 26, 1956Ser. No. 573,785 7 Claims. (Cl. SAI-1.22)

This invention relates in general to electronic musical instruments, and in particular to an arrangement for producing a chorus or celeste effect in an electronic organ.

It is well known in both the pipe organ and electronic organ fields that the chorus or celeste effect which occurs due to the beating of two notes which are slightly out of tune to one another, is a very beautiful eiect. in the pipe organ, where even the smallest instrument will have a number of sets of pipes, and which will normally be slightly out of tune to each other, this chorous edect is commonplace. But in the electronic organ Where, excepting in the very largest instruments, there is provided only one generator, and therefore only one tone source for each note of the instrument, this effect is not normally possible. In larger electronic organs where more than one tone source is provided for each note the effect is possible, and it is very effective, especially when the two notes are played through separate amplifiers and speakers. However, an electronic organ of this type is very costly. In a large organ of this type, it is customary to provide 'the instrument with two keyboards or manuals, and to provide a separate electronic oscillator or other tone source for each note of each manual. Therefore, an organ having two standard manuals of sixty one keys each, would require two generators, having a total of vnot less than one hundred and twenty two oscillators, if the chorus or celeste effect is to be achieved.

Normally, the most expensive part of the electronic organ is the generator which contains the `electronic oscillators for the instrument. in an instrument where one tone source is provided for each musical frequency, the

enerator facilities would have to be doubled in order `to :rovide the chorus effect, and the cost would be greatly increased.

An object of this invention is to provide in an instrument of no more than average cost, this very desirable chorus effect. In my copending United States patent application Serial Number 407,223, tiled on February l, 1954, entitled Electrical Musical Instrument, now issued as U.S. Patent No. 2,905,905 a simplified method is disclosed whereby a single electronic oscillator may be made to generate selectively, either of two adjacent notes of the keyboard. The oscillator is therefore shared by two notes, and in the event that both of the keys are depressed simultaneously, only the higher of the two notes will sound. The system may be extended to include three notes, or even more if desired. While admittedly this imposes a musical limitation upon the organ, still it is not a serious limitation and it makes possible a very useful organ at a much lower cost. Using shared oscillators arranged to play either of two adjacent notes, it thus becomes possible to construct a two manual electronic organ, in which a separate generator is provided for each manual, but in which the total number of oscillators is no greater than that required in a conventional organ not using shared oscillators, and having but a single manual. The desired chorus effect thus becomes possible in an organ of moderate cost as the direct result of 2,949,804 Patented Aug. 23, 1960 the employment of the shared oscillator principle, and may be achieved by playing similar chords simultaneously on the two manuals.

Another object of this invention which arises as the result of using separate generators for the two manuals, is to provide a separate expression pedal for cach manual.

Another object also arising from the use of separate generators is to provide in conjunction with the chorus effect, a three dimensional sound, or stereo effect, through use of separate amplifiers and speakers for each manual and tone generator.

Another object is to provide means whereby the expression for two manuals may be controlled with a single expression pedal when desired.

Another object is to provide means whereby normal expression may be used on one manual, while reversed expression is simultaneously used on the other manual, both operable from one expression pedal.

Another object is to provide means for slightly detuning all the oscillators of one of the generators, to enhance the chorus effect when desired.

'Other objects of the present invention will become apparent by reference to the following description taken in connection with the accompanying drawing, in which: the figure is a schematic circuit drawing of one form of the invention.

It is traditional in pipe organ construction to provide separate organs for each manual of the instrument. In this arrangement the pipes which are playable from the Great or lower manual, are often spatially separated of the room in which the organ is installed. This mparts a three dimensional feeling to the music, and at the same time permits greater clarity of musical rendition, since the passages played upon the Great and Swell manuals' are originating in diierent parts of the room.

installation, where all the sounds originate in the small space occupied by one loud speaker. The very beautiful string celeste of the pipe organ is obtained when two pipes of string tone quality are played simultaneously, either from the same manual, or from different manuals. In the latter case the two sets of string pipes may be in difierent parts of the room, which enhances the three dimensional or stereo effect.

In an electronic .organ constructed in accordance with the present disclosure, much of the beauty of the string celeste, as well as the spatial feeling of the pipe organ, may be provided in an instrument of moderate cost.

The schematic circuit diagram of the single tigure `of the drawing illustrates the essential circuit elements required to obtain the effects described herein. In general the present disclosure comprises the combination of a two manual electronic organ, in which a generator is provided for each manual to obtain the celeste effect, each generator comprising a plurality of oscillators of the shared oscillator type described in the aforementioned patent application, each oscillator being shared by at least two playing keys, a separate expression pedal for each manual, a separate amplifier and speaker for each manual to obtain the stereo effect, a switch for connecting the two amplifying systems together for maximum output, another switch for shifting the frequency slightly, of all the oscillators for one manual to enhance the celeste effect, a three circuit jack for connecting a pair of headphones to the ampliers to obtain the stereo effect with headphones, and a ganged expression pedal arrangement permitting normal expression on one manual and reversed expression on the other manual.

Referring to the drawing, the Swell manual and generator are represented at 1 by a single oscillator and its asresistor 18, will be connected to the oscillators in the Swellgenerator.

sociated key switches. The Great manual and generator are represented at 2 by a single oscillator and its associated key switches. The expression control for the Swell is shown at 22, and the Great expression control is 28. The Swell ampliiier and speaker are 37 and 4t), while the Great amplier and speaker are 38 and 39. The circuit operation of the shared oscillators 1 and 2 was completely described in the previously mentioned patent application, and will be discussed only briefly herein. These two loscillators are identical and are tuned to the same frequencies, for example C and C#. In the drawing like reference characters have been used for 'like elements in each of the Swell generator oscillators and the Great generator oscillators. The other oscillators in each generator are similar to those shown excepting for the values of the circuit components, as required for the different frequencies to beplayed by the manuals.

Each of the oscillators is a conventional Hartley, having .triode 3, parallel tuned circuit 5, 6, grid blocking capacitor 7, cathode cut off biasing resistors 8 and 9, plate resistor 10, output coupling capacitor 11 and, output coupling resistor 12. Resistor 12 of the Swell manual oscillator connects to the Swell signal common output bus t), to which as indicated are connected all other output resistorrs 12 of the Swell generator. This bus carries the combined output signals of all the oscillators of the Swell generator to the Swell amplifier 37 via the switch 19--20 and resistor 24. The signals are carried from the amplifier to speaker 37 via the switch 44-45.

Similarly, the Great oscillator 2 is connected to common Great signal output bus 51, through resistor 27 to Great ampliier 38, and from there through switch 4-1-42 to Great speaker 39.

All oscillators because the grids are held at cut oi by means of cathode biasing resistors 8 and 9, are normally inoperative until a playing key is depressed, closing its associated key switch. The grid of the Swell oscillator 1 which is normally held at ground potential through a grid resistor 4, is thus raised into the operating region by the application of the positive keying potential appearing at terminal 15. When for example key switch 16 is closed,

.this positive potential is applied through variable tuning resisto-r 13 and the closed contacts of switch 16, through the closed contacts of switch 17, to the grid of triode 3. This initiates oscillation at a frequency determined by, the Value of capacitor 14 in shunt with the tuned circuit 5 and 6, and also the grid bias, which is determined by the Value of the variable tuning resistor 13. The useful tuning range of this tuning control is about one semitone. If key switch 17 is closed the frequency of oscillation will be higher because there is now no capacitor 14 in the circuit. Variable resistor 52 functions similarly to resistor 13, as a ne tuning control.

It will be apparent that the value of resistor 4, and the potential to which it is returned, will influence the frequency of oscillation. As indicated, all Grid resistors 4 of the Swell oscillators, are connected to the common lead 54. This lead connects to resistor 55 and also to contact point 36 of the stereo switch, which is normally j grounded through switch arm 34. Thus when the stereo switch is in the normal position as shown, all Swell oscil- .lator grid resistors 4 return to ground, and with the switch in this position the oscillators of the Swell generator are tuned to the same frequencies as the corresponding oscillators in the Great generator. All Great oscillator grid resistors, as represented by resistor 53 of oscillator 2, of the Great generator, are returned to ground. Thus when key switch 16 of the Swell manual is closed at the same time as key switch 56 of the Great manual, little or no beat is audible between the two oscillators, for

v,each is tuned exactly to the :no-te C. If however, the

stereo switch is now operated to the stereo position, lead 54 will be disconnected from ground, and a small positive potential derived through resistor 55 from adjustable grid resistors 4 of all This will cause the of all oscillators in the Swell generator to rise slightly, and a beat will now be heard between oscillators 1 and 2. The beat rate is adjustable, and is controlled by the adjustment of resistor 18 A beat rate of approximately one per second is found to be very pleasing, although this is not critical.

Thus it will be seen that with the stereo switch in the normal position, little or no beating will occur between similar notes on the two manuals, but with the switch in the stereo position, a pleasing beating or celeste etrect will be heard, when similar chords are played simultaneously on the two manuals.

It will be seen that when the stereo switch is in the stereo position the switch arm 34 grounds the contact point 35. When this contact is not grounded the Swell amplifier 37 receives signal not only from the Swell generator but also from the Great generator through resistors 25 and 26 in series. Similarly the Great amplifier 38 receives signals not only from the Great generator, but also from the Swell generator through resistors 25 and 26, and both manuals are thus enabled to play through both amplifiers and speakers for maximum power output. When switch contact 35 is grounded however, the common terminal between resistors 25 and 26 is grounded, and thus no interchange of signals between the two manuals can take place. Therefore with the switch in the stereo position, each manual plays only through its own amplier and speaker. The spatial separation of the tones from the two manuals thus achieved, together with the celeste or chorus, provides a very delightful musical effect. The stereo switch is adapted to be operated by means of a stop tablet on the control panel of the organ, so that the player may change instantly from the normal position, with both manuals playing through both amplifiers, to the stereo position, and back again, as desired.

In the figure at 22 is an adjustable resistor, controlled by a foot operated expression pedal associated with the Swell manual. This resistor, in series with bass compensating capacitor 23, -acts as a variable shunt between the signal bus 50 and ground, to control the signal amplitude reaching the amplifier 37 from the Swell generator. This effects occurs when the switch arm 19 is normally connected to switch contact 26 as shown. When this switch is in the other position, switch arm 19 connects to contact 21, causing resistor 22 to be disconnected and replaced by variable resistor 30, as expression control. Resistor 30 is of similar resistance value and of similar function as resistor 22. However, resistor 30 is operated by the Great expression pedal, and is ganged to the Great expression control 28, as indicated. When selector switch arm 32 connects to contact 33 as shown, normal expression control of the signals from the Swell generator to the amplifier 37 takes place, excepting that the action is controlled by the Great expression pedal, instead of the Swell expression pedal. With switch arm 32 connecting to contact 31 however, the normal expression action is reversed, so that the Swell signals decrease instead of increasing, when the Great expression pedal is advanced.

The action of the Great expression control 28 is normal, and it serves to control the amplitude of signals from the Great generator to the amplifier 38. Thus with the three controls and two switches functioning as described, it is possible to have, (l) separate expression control for each manual, (2) ganged normal expression frequencies control for both manuals, operated by means of the novel arrangement giving a greater degree of dynamic contrast between the two manuals. It is useful for simulated percussive effects and for other cases where it is desired to provide sudden changes in contrast between the two manuals. It is especially useful also where a solo is played on one manual and the accompaniment is played on the other manual. For example suppose that a string solo is played on the Great, and a fiute accompaniment is played on the Swell. Using the first condition of separate expression for each manual, the player would probably set the Swell fiute to a desired level and then leave it there, and place most of the expression during the playing of the piece, on the string solo. Any change in contrast between the fiute and string would occur only as a result of rise and fall in amplitude of the string solo. But in the third case, where reverse expression is used on the Swell, the amplitude of the fiute accompaniment would fall as the string amplitude increased, or the reverse, depending upon the movement of the expression pedal. It will thus be seen that the range of expression has been increased without increasing the overall amplitude range of the instrument.

Referring to the figure, a speaker switch having a pair of ganged switches is shown, connected to the output terminals of the amplifiers 37 and 38. Switch arm 44 in its normal position as shown, connects through contact 45, the Swell amplifier 37 to the Swell speaker 40. Similarly switch arm 41 in its normal position connects the Great amplifier 3S through contact 42 to the Great speaker 39. Thus when the switch is in its normal position, the organ plays through two speakers as described. These two speakers may both be placed in the organ console, or one or both speakers may be installed in separate tone cabinets, and placed a distance from the organ. The stereo effect may be enhanced by locating the speaker tone cabinets at opposite ends of the room in which the organ is installed, and with the organ console locatedv midway between them.

The organ may be used for silent practice by operating the speaker switch to the other position. In this position the ouput of the Swell amplifier 37 is disconnected from the speaker and connected through switch contacts `44 and 46 to a three circuit jack 47. Similarly the output of Great amplifier 38 is disconnected from its speaker and is connected through switch contacts 41 and 43 to jack 47. By means of the use of conventional head phones 49 fitted with a three circuit cord and plug 48, which is inserted into the jack y47, the stereo or binaural effect may be obtained, and the tones Ifrom one manual will be heard in one ear, while the tones from the other manual will be heard in the other ear. Both speakers are of course inoperative with this arrangement, and only the person listening to the head phones will hear the tones from the organ.

When a 6I5 tube is employed as oscillator triode 3, and the keying potential 15 is 40 to 70 volts, and the B+ voltage is 150 volts, suitable values for the components of Figure 1 are as follows, for oscillation frequencies of C 261.6 cycles and C# 277.2 cycles per second:

5 henries l0 6 mf .03 7 mf-- .05 11 mf .02 14 mf .004 23 and 29 t mf-.. .5 4 ohms 500K 8 do 2,200 9 do 15K 10 do 100K 12 do 100K 13 megohms 1.5 18 ohms 5,000 22 do `500K 6 24 do 100K 25 do 56K 26 do 56K 27 do 100K 28 do 500K 52 megohms 1.5 53 ohms 500K 55 do 5,000 57 do 56K While for the purpose of illustrating and describing the present invention, certain preferred embodiments have been shown, it will be apparent to those skilled in the art that various modifications may be made, including the use of other types of shared oscillator circuits, such as that shown in my disclosure in United States Patent Number 2,203,432, without departing from the basic principles of the invention. I therefore do not wish to be limited to the precise details set forth herein, but desire to include within the scope of the invention those modified forms by means of which similar results may be obtained in substantially the same way.

Having thus described my invention, I claim as follows:

l. In an electronic organ, the combination comprising a plurality of oscillators, a first manual having associated switching means, a second manual having associated switching means, means interconnecting said oscillators and said switching means for actuating said oscillators, a first amplifier, a first speaker coupled to said first amplier, a second amplifier, a second speaker coupled to said second amplifier, a first expression control coupled between said first manual and said first amplifier, a second expression control coupled between said second manual and said second amplifier, means linking said first expression control to said second expression control whereby both said controls may be operated simultaneously, and a selector switch connected to said first expression control for selectively reversing the effect of the first expression control on said rst manual with respect to the effect of the second expression control on the second manual.

2. In an electronic organ, the combination comprising a rst electronic generator, a second electronic generator, a first manual having associated key switches connected to the first electronic generator, a second manual having associated key switches connected to the second electronic generator, said first generator comprising at least one shared oscillator adapted to oscillate at a plurality of musical frequencies under selective control of at least two key switches of said first manual, said second generator comprising at least one shared oscillator adapted to oscillate at a plurality of musical frequencies under selective control of at least two key switches of said second manual, a first amplifier, a first speaker coupled to said first amplifier, a second amplifier, a second speaker coupled to said second amplifier, a rst connecting means between said first generator and said rst amplifier, a second connecting means between said second generator and said second amplifier, said rst connecting means including an amplitude control means comprising an adjustable resistance connected serially with a fixed reactance, said second connecting means including an amplitude control means comprising an adjustable resistance connected serially with a fixed reactance, a third connecting means comprising two resistances serially connected and having a common junction terminal, said third connecting means being connected between said first connecting means and said second connecting means and a switch connected to said juction terminal for disabling said third connecting means.

3. In an electronic organ, the combination of: first means for producing selected audible musical tones comprising; a source of oscillatory wave energy productive of discrete electrical signals having frequencies corresponding to the notes of a musical scale, said source being in turn coupled to both a first sound producing system having an amplifier and loud speaker and a first manual having associated switching Vmeans for selectively controlling the frequencies of the electrical signals coupled to said first sound producing system, said first means also including expression controlling second means for controlling the expression of the musical tones produced by the lloud speaker of said first sound producing system, third means for producing selected audible musical tones comprising; a source of oscillatory wave energy productive of discrete electrical signals having frequencies corresponding to the notes of a musical scale, said source being in turn coupled to both a second sound producing system having an amplifier and loud speaker and a second manual having associated switching means for selectively controlling the frequencies of the electrical signals coupled to said second sound producing system, said third means also including expression controlling fourth means for controlling the expression of the musical tones produced by the loud speaker of said second sound producing system; and means linking said second `and said fourth means for permitting said second and fourth means to be operated simultaneously to produce respectively opposite effects on the expression control imposed on musical tones produced by said first and third means.

4. In an electronic organ the combination of: a first source of oscillatory wave energy productive of discrete electrical signals having frequencies corresponding to the notes of a musical scale; a first sound producing system comprising: a first audio amplifier connected in driving relation to a first loud speaker; a first manual; means coupling said first source of oscillatory wave energy to both said first manual and to said first sound producing system for permitting said first manual to selectively control the frequencies of the electrical signals coupled to said first sound producing system; `a second source of oscillatory wave energy productive of discrete electrical signals having frequencies corresponding to the notes of a musical scale; a second sound producing system comprising; `a second audio amplifier connected in driving relation to a second loud speaker; a second manual; means coupling said second source of oscillatory wave energy to both said second manual and to said second sound producing system for permitting said sec` ond manual to selectively control the frequencies of the electrical signals coupled to said second sound producing system; frequency shifting means coupled to said first source of oscillatory wave energy for shifting the frequencies of all of the electrical signals produced thereby by a specified amount with respect to the frequencies of .the electrical signals produced by said second source of oscillatory wave energy; mixing means coupled to said first and said second sound producing systems for mixing the signals applied to both said first and said second sound producing systems to permit each of said sound producing systems to receive electrical signals from both of said sources of Wave energy; a switching system having a first position and a second position; and means coupling said switching system in controlling relation to both said frequency shifting means and said mixing means for selectively controlling the operations of said frequency shifting means and said mixing means. t

5. In an electronic organ the combination of: a first source of oscillatory wave energy including a plurality of frequency shared oscillators and productive of discrete electrical signals having frequencies corresponding to the notes of a musical scale; a first sound producing system comprising: a first audio amplifier connected in driving relation to a first loud speaker; a first manual; means coupling said first source of oscillatory Wave energy to both said first manual and to said first sound producing system for permitting said first manual to selectively control the frequencies of the electrical signals coupled to said first sound producing system; aV

second source of oscillatory wave energy including a plurality of frequency shared oscillators productive of discrete electrical signals having frequencies corresponding to the notes of a musical scale; a second sound producing system comprising: a second audio amplifier connected in driving relation to a second loud speaker; a second manual; means coupling said second source of oscillatory wave energy to both said second manual and to said second sound producing system for permitting said second manual to selectively control the frequencies of the electrical signals coupled to said second sound producing system; frequency shifting means coupled to said first source of oscillatory wave energy for shifting the frequencies of all of the electrical signals produced thereby by a specified amount with respect to .the frequencies of the electrical signals produced by said second source of oscillatory w-ave energy; mixing means coupled to said first and said second sound producing systems for mixing the signals applied to both said first and said second sound producing systems to permit each of said sound producing systems to receive electrical signals from both of said sources of wave energy; a switching system having a first position and a second position; and means coupling said switching system in controlling relation to both said frequency shifting means and said mixing means for selectively controlling the operations of said frequency shifting means and said mixing means.

6. In an electronic organ the combination of: a first source of oscillatory wave energy productive of discrete electrical signals having frequencies corresponding to the notes of a musical scale; a first sound producing system comprising: a first audio amplifier connected in driving relation to a first loud speaker; a first manual; means coupling said first source of oscillatory wave energy to both said first manual and to said first sound producing system for permitting said first manual to selectively control the frequencies of the electrical signals coupled to said first sound producing system; a second source of oscillatory wave energy productive of discrete electrical signals having frequencies corresponding to the notes of a musical scale; a second sound producing system comprising: a second audio amplifier connected in driving relation to a second loud speaker; a second manual; means coupling said second source of oscillatory wave energy to both said second manual and to said second sound producing system for permitting said second manual to selectively control the frequencies of the electrical signals coupled to said second sound producing system; frequency shifting means coupled to said first source of oscillatory wave energy for shifting the frequencies of all of the electrical signals produced thereby by a specified amount not substantially greater than one semi-tone in the musical scale of said first source of oscillatory wave energy with respect to the frequencies of the electrical signals produced by Said second source of `oscillatory wave energy; mixing means coupled to said first and said second sound producing systems for mixing the signals applied to both said first and said sec- ;ond sound producing systems to permit each of said sound producing systems to receive electrical signals from both of said sources of wave energy; a switching system having a first position and a second position; and means coupling said switching system in controlling relation to both said frequency shifting means and said mixing means for selectively controlling the operations of sa1d frequency shifting means and said mixing means.

7. ln an electronic organ the combination of: a first `source of oscillatory wave energy productive of discrete electrical signals having frequencies corresponding to the notes of :a musical scale; a first sound producing system comprising: a first audio amplier connected in driving relation to a first Vloud speaker; a first manual; means coupling said first source of oscillatory wave energy to kboth said first manual and to said first sound producing system for permitting said first manual to selectively control the frequencies of the electrical signals coupled to said rst sound producing system; a second source of oscillatory wave energy productive of discrete electrical signals having frequencies corresponding to the notes of a musical scale; a second sound producing system comprising: Ia second audio amplifier connected in driving relation to `a second loud speaker; a second manual; means coupling said second source of oscillatory wave energy to both said second manual and to said second sound producing system for permitting said second manual to selectively control the frequencies of the electrical signals coupled to said second sound producing system; frequency shifting means coupled to said rst source of oscillatory wave energy for shifting the frequencies of all of the electrical signals produced thereby by a specified amount with respect to the frequencies of the electrical signals produced by said second source of oscillatory wave energy; mixing means coupled to said first and said second sound producing systems for mixing the signals yapplied to both said first and said second sound producing systems to permit each of said sound producing systems to receive electrical signals from both of said sources of wave energy; a switching system having a rst position and a second position; and means coupling said switching system in controlling relation to both said frequency shifting means and said mixing means lfor selectively controlling the operations of said `frequency shifting means and said mixing means so that said frequency shifting means is enabled and said mixing means disabled for one position of said switching systems, and said shifting means is disabled and said mixing means enabled for the other position of said switching system.

References Cited in the le of this patent UNITED STATES PATENTS 1,855,149 Jones Apr. 19, 1932 2,305,574 Koehl Dec. 15, 1942 2,310,429 Hanert Feb. 9, 1943 2,463,597 Cahill Mar. 8, 1949 2,500,820 Hanert Mar. 14, 1950 2,542,065 Wye Feb. 20, 1951 2,583,566 Hanert Jan. 29, 1952 2,681,585 Hanert June 22, 1954 

